Incessant Atrial Tachycardia From the Left Atrial Appendage Treated With Appendage Ligation

A previously healthy man presented in shock due to incessant tachycardia. He ultimately required extracorporeal membrane oxygenation for support and clipping of his appendage for arrhythmia control. This case highlights the importance of early recognition of cardiogenic shock, aggressive hemodynamic support, and a multidisciplinary approach to managing these challenging arrhythmias.

wide complex tachycardia.He reported several months of worsening shortness of breath and feeling of heart racing.On arrival to an outside emergency department, his 12-lead electrocardiogram showed him to be in atrial tachycardia with left bundle branch block (Figure 1A).Cardioversion was attempted with prompt recurrence of arrhythmia shortly after cardioversion.He was given amiodarone bolus and infusion.Cardioversion was reattempted with recurrence, and he was transferred to our institution.

PAST MEDICAL HISTORY
He was an otherwise healthy, active man who had been able to exercise regularly until a few months prior to presentation.Of note, he did report a history of "tachycardia" diagnosed in his teens that required a cardioversion; however, no other information or records were available other than his own recollection of events.

DIFFERENTIAL DIAGNOSIS
The differential diagnosis for young healthy patients with a wide complex tachycardia includes ventricular tachycardia vs supraventricular tachycardia with aberration, as this patient's electrocardiogram suggested.Etiologies for tachycardia include bypass tract

LEARNING OBJECTIVES
To make a differential diagnosis for incessant tachycardia.To keep in mind the difficulty in managing incessant automatic atrial tachycardias that may require unconventional therapy with either ivabradine or surgical intervention.

DISCUSSION
We present a case of severe systolic dysfunction and cardiogenic shock due to an incessant atrial tachycardia that was refractory to cardioversion, ablation, amiodarone, and ivabradine and ultimately required left atrial appendage clipping for treatment.Focal atrial tachycardias can arise from anywhere within the 2 atria; however, locations within the pulmonary veins and appendages have a particularly high frequency of becoming incessant and more frequently cause tachycardia mediated cardiomyopathy than other foci. 1 Both medical therapy and catheter ablation are established therapies for controlling focal tachycardias from the appendages. 2 The use of ivabradine to control focal tachycardias has been reported in the literature, [3][4][5][6][7][8] with 1 larger case series documenting a significant percentage of treatment failure that requires catheter ablation for eventual control. 9Ivabradine works by inhibiting the "funny current" I f , which mediates phase 4 depolarization in pacemaker tissues. 10

FUNDING SUPPORT AND AUTHOR DISCLOSURES
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.jon.melman@imail.org.

R E F E R E N C E S
Given his drug refractory incessant atrial tachycardia and severely diminished ejection fraction, we made the decision to attempt catheter ablation.With cardiac anesthesia and the cardiac surgery team available for emergent hemodynamic support in case of decompensation, the patient was brought to the catheterization laboratory under light conscious sedation.The surface P-wave morphology was difficult to appreciate in the setting of tachycardia and wide left bundle branch block with secondary repolarization abnormality.However, activation in the coronary sinus was from distal to proximal.Ventricular overdrive pacing maneuvers confirmed the arrhythmia to be an atrial tachycardia.We then mapped a focal atrial tachycardia to the tip of the left atrial appendage.Earliest activation preceded the surface P-wave by approximately 35 milliseconds (Figure2A).The unipolar signal was consistent with the catheter being near the site of origin.With the application of radiofrequency (RF) energy, there was termination to sinus rhythm within 1 second (Figure2B).Lesions were applied at 10g to 20g of force, and 30 W of RF was used.Given the location deep within the appendage and the potentially catastrophic implications of a perforation, we were

FIGURE 1
FIGURE 1 12-Lead Electrocardiogram During the Patient's Admission

FIGURE 2
FIGURE 2 Mapping and Ablation of Tachycardia I f is responsible for phase 4 depolarization in the sinoatrial and atrioventricular nodes, and has also been described in Purkinje cells in both atria and ventricles.It may explain the sensitivity of ectopic rhythms to the medication.In the largest published case series, a significant proportion of patients experienced transient or no response to the arrhythmia and required catheter ablation for definitive treatment of the arrhythmia.In this case, ivabradine was ultimately unsuccessful in providing definitive arrhythmia control; nonetheless, the transient control of heart rate allowed for at least some myocardial recovery and hemodynamic stabilization.Our previous activation map had localized the focus of the tachycardia to be in the distal aspect of the left atrial appendage; we therefore decided to proceed with left atrial appendage clipping to exclude the tachycardia focus.Clipping of the appendage to treat a focal tachycardia has been reported only once before in the literature. 11The present case illustrates both the importance of prompt recognition and management of impending cardiogenic shock from tachycardia mediated cardiomyopathy and the use of pharmacologic, ablative, and surgical techniques in managing difficult-to-treat arrhythmias.FOLLOW-UP Since discharge, the patient has not had recurrence of tachycardia and he monitors himself regularly at home.He reports complete resolution of all heart failure symptoms and is back to his baseline functional status.Most recent ejection fraction 5 days after tachycardia termination shows his ejection fraction in the low to normal range at 45%.CONCLUSIONS In this young patient, an incessant focal atrial tachycardia caused a tachycardia mediated cardiomyopathy which led to cardiogenic shock.Aggressive early mechanical support and treatment with ivabradine allowed for sufficient stabilization and myocardial recovery and was able to go through an appendage clipping to control his arrhythmia.